The invention relates to a method of and to an apparatus for manipulating block-shaped objects, such as packs of cigarettes, cigarillos, cigars and other rod-shaped smokers' products. A similar apparatus is disclosed in commonly owned U.S. Pat. No. 4,243,135. More particulary, the invention relates to improvements in a method of and in an apparatus for replacing defective objects in a stream of objects wherein satisfactory and defective objects are distributed in random fashion. Still more particularly, the invention relates to improvements in a method of and in an apparatus for replacing defective objects in a stream wherein defective and satisfactory objects form a series of neighboring stacks of overlapping satisfactory, defective and/or satisfactory and defective objects.
It is well known to directly couple two machines in a production line which turns out cartons or bundles of packs of cigarettes, cigarillos or cigars (hereinafter referred to as cigarette packs). For example, it is known to directly couple a machine which provides cigarette packs with outer envelopes of transparent or translucent material (called wrapper machine) with a case packer or with a carton packing machine. The path between the two machines normally extends along a mechanism which is used to remove defective packs so as to ensure that the case packer or the carton filler receives only satisfactory packs, namely packs whose outer envelopes are acceptable in each and every respect. This involves a monitoring of the packs ahead of the ejecting station and the generation of signals which are used to initiate the ejection of corresponding packs from their path in order to ensure that the defective packs (e.g., those having projecting portions of outer envelopes, those without outer envelopes and/or those having soiled or otherwise unacceptable outer envelopes) cannot reach the case packer or the carton filling machine.
The case packer or the carton filling machine operates properly only if it receives stacks of satisfactory packs. This necessitates expulsion of all stacks which consist exclusively of defective packs as well as completion of all stacks which contain defective and satisfactory packs by replacing each defective pack with a satisfactory pack. Gaps which develop in the stream of stacks advancing toward the case packer or toward the carton filling machine as a result of expulsion of one or more complete stacks by advancing the trailing (satisfactory) stacks with reference to the preceding (satisfactory) stacks. The completion of stacks which contained satisfactory and defective packs and from which defective packs were expelled presents greater problems because it is necessary to insert a satisfactory pack in lieu of each expelled defective pack.
Proposals to solve the above problem include the expulsion of each stack which consists exclusively of defective packs as well as to expel each stack which contains one or more satisfactory and one or more defective packs. Such proposals failed to gain acceptance in the industry because the number of expelled packs is excessive.
Another proposal is disclosed in the published British patent application Ser. No. 2 150 520 A of Boyce who proposes to expell all stacks which contain one or more defective packs and to replace the expelled stacks with spare stacks consisting of satisfactory packs which were recovered from expelled stacks with satisfactory and defective packs. Spare stacks are obtained from a pile which consists of receovered satisfactory packs and is gathered by hand. Such proposal is not entirely satisfactory because it involves manual work and cannot ensure the refilling of gaps in an automated production line which must turn out large numbers of smokers' articles, e.g., up to and in excess of 400 packs per minute.